User-friendly analytical devices such as Paper Analytical Devices (PADs) are known in the art as convenient and inexpensive means for assaying chemicals. As these devices contain all necessary reagents and do not require power, they are easy to operate in a field setting. U.S. Pat. No. 6,136,549 discloses systems for conducting spectrophotometric analysis which includes a chromatographic medium, such as an assay test strip, that is designed to be contacted with a test solution having activated magnetic particles. U.S. Pat. No. 6,770,487 discloses “dip stick” style paper-based diagnostic test devices, in which identifying information and the test result are machine-readable. U.S. Pat. No. 6,847,451 discloses apparatuses for determining the concentration of an analyte in a physiological sample, which include at least one light source, a detector array, means for determining whether a sufficient amount of sample is present on each of the plurality of different areas, and means for determining the concentration of the analyte based on the reflected light detected from those areas determined to have sufficient sample. U.S. Pat. No. 7,344,081 discloses a method of automatically detecting a test result of a probe zone of a test strip comprising capturing an image of a one-dimensional bar code and an image of at least one test strip from a scanning object, and determining a setting value for the at least one test strip based, at least in part, on said captured image of said bar code. U.S. Pat. No. 7,885,444 discloses a method for determining a response of each probe zone on a test strip by selecting an average pixel value of each section of reference white respectively adjacent to the image of a target line to serve as a reference for determining a color response of the target line. US Publication No. 2008/0012083 discloses an analytical system-on-a-chip that can be used as an analytical imaging device, for example, for detecting the presence of a chemical compound, which may also include software that can detect and analyze the output signals of the device. US Publication No. 2011/0189786 discloses a method of detecting the presence or absence of an analyte in a fluid sample. The method includes applying the sample to an inlet zone of a diagnostic system that includes a hydrophilic cotton loading thread to serve as a capillary to deliver a solute to a reagent testing zone, and detecting color change of reagent analyte interaction. US Publication No. 2011/0111517 discloses a paper-based microfluidic assay device comprising a porous, hydrophilic substrate; a fluid-impermeable barrier defining a boundary of an assay region and a boundary of a main channel region, the main channel region fluidically connected to the assay region; and a strip of conductive material disposed on the porous, hydrophilic substrate for detecting the concentration/flow of analyte. In a commercial embodiment, pSiFlow Technology Inc. provides a mobile testing and process management web infrastructure built around its Calibrated Color Match (CCM) image processing technology that enables digital reading of color-based test strips using any mobile phone with a camera.
The World Health Organization (WHO) reports that many medications for sale in underdeveloped countries are of low quality, which either contain low concentrations of active ingredients that are not sufficient to treat the underlying condition, or contain substitute active ingredients that may have adverse effects on some patients, or have no active ingredients at all; or even contain toxic ingredients. Although the prevalence of such medications is difficult to measure, both the WHO and US Food and Drug Administration (FDA) estimate that 10-30% of all drugs in the developing world are low quality drugs. A consumer taking a low quality pharmaceutical product may die or experience other adverse medical effects from the underlying condition or from contaminants in the pharmaceutical product. The failure of treatment may be mistaken for resistant strains of the disease requiring much more rigorous treatment that can itself endanger the patient. Also, low quality medications that fail to cure the underlying condition may speed up development of actual resistance in pathogens.
Multiple factors contribute to the prevalence of low quality pharmaceutical products in developing countries. First of all, manufacturing and selling low quality pharmaceutical products are both easy and hugely lucrative, and low quality products can enter the supply chain at many points. Moreover, buyers and consumers cannot assess identity or quality of pharmaceutical products. Furthermore, manufacturing low quality pharmaceutical products is not a serious crime in many countries, and there is a low risk of detection from official agencies and organizations. Finally, the time, expertise, and expense required for testing pharmaceutical products is a particular barrier to effective post-market surveillance of pharmaceuticals in developing countries.
Some medical conditions arise not from a pathogen, but from a deficiency in an essential nutrient. For example, widespread iodine deficiency is a problem in many underdeveloped countries that is associated with developmental impairment in children. Fortification of table salt with potassium iodate or potassium iodide is a common route to address this problem. However, production and distribution methods for iodized table salt in many developing countries yield inadequate or inconsistent levels of iodine. Unfortunately, the time and expense of testing for iodized table salt deters manufacturers, distributors, and end-users from testing iodized table salt to determine iodine concentrations. Thus, a low-cost method of testing iodized table salt at the production facility or in the field is needed to determine whether the salt is adequately fortified with iodine within therapeutic concentrations recommended by the WHO.
Thus, there exist long-felt needs for a low-cost, easy-to-use, reliable, minimalistic chemical means of detecting low quality pharmaceutical products and dietary supplements such as iodized salt. These quality problems are also present for veterinary medications and nutritional supplements for animals. The present invention addresses these needs by providing an inexpensive, user-friendly, consistent analytical device capable of detecting various low quality pharmaceutical products and measuring levels of iodine in iodized salt.